Remove compatibility with Python < 3.8

... because this library now supports only Python 3.8 or newer
versions.

Change-Id: Ibb48af4c501946b62a244994ecea5bfcd998810c

oslo_config/generator.py

@@ -25,6 +25,7 @@ Tool for generating a sample configuration file. See
 
 import collections
 import copy
+import importlib.metadata
 import json
 import logging
 import operator
@@ -42,12 +43,6 @@ except ImportError:
 
     rst2txt = None
 
-try:
-    # For Python 3.8 and later
-    import importlib.metadata as importlib_metadata
-except ImportError:
-    # For everyone else
-    import importlib_metadata
 
 import yaml
 
@@ -822,7 +817,7 @@ def generate(conf, output_file=None):
 
 def main(args=None):
     """The main function of oslo-config-generator."""
-    version = importlib_metadata.version('oslo.config')
+    version = importlib.metadata.version('oslo.config')
     logging.basicConfig(level=logging.WARN)
     conf = cfg.ConfigOpts()
     register_cli_opts(conf)

oslo_config/validator.py

@@ -21,17 +21,11 @@ the provided file.  If there are any options set that are not defined in the
 project then it returns those errors.
 """
 
+import importlib.metadata
 import logging
 import re
 import sys
 
-try:
-    # For Python 3.8 and later
-    import importlib.metadata as importlib_metadata
-except ImportError:
-    # For everyone else
-    import importlib_metadata
-
 import yaml
 
 from oslo_config import cfg
@@ -224,7 +218,7 @@ def _validate(conf):
 
 def main():
     """The main function of oslo-config-validator."""
-    version = importlib_metadata.version('oslo.config')
+    version = importlib.metadata.version('oslo.config')
     logging.basicConfig(level=logging.INFO)
     conf = cfg.ConfigOpts()
     _register_cli_opts(conf)

requirements.txt

@@ -9,4 +9,3 @@ oslo.i18n>=3.15.3 # Apache-2.0
 rfc3986>=1.2.0 # Apache-2.0
 PyYAML>=5.1 # MIT
 requests>=2.18.0 # Apache-2.0
-importlib_metadata>=1.7.0;python_version<'3.8' # Apache-2.0